Tumor necrosis factor alpha-induced activation of downstream NF-kappa B site of the promoter mediates epithelial ICAM-1 expression and monocyte adhesion: Involvement of PKC alpha, tyrosine kinase, and IKK2, but not MAPKs, pathway

TNF-alpha induced an increase in intercellular adhesion molecule-1 (ICAM-1) expression in human A549 epithelial cells and immuno fluorescence staining confirmed this result. The enhanced ICAM-1 expression was shown to increas e the adhesion of U937 cells to A549 cells. Tyrosine kinase inhibitors (gen istein or tyrphostin 23) or phosphatidylcholine-specific phospholipase C (P C-PLC) inhibitor (D 609) attenuated TNF-alpha -induced ICAM-1 expression. T NF-alpha produced an increase in protein kinase C (PKC) activity and this e ffect was inhibited by D 609. PKC inhibitors (staurosporine, Ro 31-8220, ca lphostin C, or Go 6976) also inhibited TNF-alpha -induced response. 12-O-Te tradecanoylphorb ol-13-acetate (TPA), a PKC activator, stimulated ICAM-1 ex pression, this effect was inhibited by genistein or tyrphostin 23. Treatmen t of cells with TNF-alpha resulted in stimulation of p44/42 NL, MAPK, p38, and JNK. However, TNF-alpha -induced ICAM-1 expression was not affected by either MEK inhibitor, PD 98059, or p38 inhibitor, SB 203580. A cell-permeab le ceramide analog, C-2 ceramide, also stimulated the activation of these t hree MAPKs, but had no effect on ICAM-1 expression. NF-kappaB DNA-protein b inding and ICAM-1 promoter activity were enhanced by TNF-alpha and these ef fects were inhibited by D 609, calphostin C, or tyrphostin 23, but not by P D 98059 or SB 203580. TPA also stimulated NF-kappaB DNA-protein binding and ICAM-1 promoter activity, these effects being inhibited by genistein or ty rphostin 23. TNF-alpha- or TPA-induced ICAM-1 promoter activity was inhibit ed by dominant negative PKC alpha or IKK2, but not IKK1 mutant. IKK activit y was stimulated by both TNF-alpha and TPA, and these effects were inhibite d by Ro 31-8220 or tyrphostin 23. These data suggest that, in A549 cells, T NF-alpha activates PC-PLC to induce activation of PKC alpha and protein tyr osine kinase, resulting in the stimulation of IKK2 and NF-kappaB in the ICA M-1 promoter, then initiation of ICAM-1 expression and neutrophil adhesion. However, activation of p44/42 NL, MAPK, p38, and JNK is not involved in th is event. (C) 2001 Elsevier Science Inc. All rights reserved.